The design of circuit disconnect switches for electrical power transmission lines presents a variety of problems, one of which is the need to connect the hinge terminal end of the switch blade to the electric power line in such a way that the blade may be pivoted relatively easily while still maintaining a substantially resistance-free electrical connection to the power line.
A typical prior art hinge terminal mounting has a portion of the blade aligned with the axis of rotation of a rotatable support upon which the blade is fixedly mounted; and a terminal connector which is adapted to be connected to a power transmission line has spaced sets of multiple leaf spring arms bearing against opposite sides of the hinge terminal end portion of the blade so that that portion of the blade rotates between the multiple leaf spring arms as the blade is opened and closed. In such a construction, the leaf spring arms are rather heavily stressed and have substantial surface areas in contact with the blade surfaces, tending to make the blade difficult to turn.
The leaf spring arms are subject to fatigue failure, particularly because of the fact that such switches are nearly always mounted in outdoor locations where they are exposed to the weather, and there is no satisfactory way to protect the leaf spring arms from the weather or to seal the contact areas between the spring arms and the blade surfaces.
Curtis et al U.S. Pat. No. 2,849,554 discloses another type of hinge terminal connection for an electric circuit disconnect switch.